



produce fumi impedsncediscontinuit! therein conductor of a super-highfrequency transmission system. is shielded from abrupt physical misionintofthe dielectric Propagation mediam therein. and therefore ,fromclose enough parallel coupling to any electromagnetic neldswhichmaybemscatthereintcauenubltamtiaidissontinuityintheimpedanceofthssystem althepotntwhcrethediodeisbuiltin feature of the invention is anzsrmgellislitofthebuilt-indiodewithavery short inta-sm spacing to aiford two simultsneousadvantages: (l) thatthcdiodewill to produce relatively largenoiseeurrentsnvarawideband of frecuencias. and (2) thatthe electronstream will not be abierto absorewh energy from any electromy existwithin the holoondilctor..ise., that the electron streaml,egnllierltothateiiergyandtherefore will notsubstantially alter theimpedance ofthe systemat the point where the diode is.'Amnsl'tinbrhamcftheinventionis an arrangement wherebythe shuntimpedance pressndtothediodebythesectionoithem- Atcwlnichrist-isbuilthasasuitably high valise for mi useful amounts of noise power.Molte anrllsmc reduction of an intermi dimensii of the hollow conductorof that sectim to preside a short discharge space forthediodawhiislatthesametimetheshuntimpedaneewhichthediodepresentstothesystem isreiativelyhighduetoitsopationwith tembiecinwillbeapparent from the folof the invention pointedout withparticulariuhtheappendedclaimsand taken in connection with theaccompanying PigJisasiderinlofanoisediodeconstructed in accordancewith-s preferred embodiment of the invention, thadiode beingincorporated into asectionofwaveguide portionsofwhichareMsanseaienspecuvnyampviewmd aant-awayldevlewofaporticnofthestruc- Pigs.s and@ represent a modification ofthe taken aiong'iine I-l armures.andlllgures being aleftendviewofmure.

Similar reference characters are applied to similar elements throughoutthe drawings.

Referring to Fig. l, the diode comprises a wave guide section l0 whichin the present embodiment is o! the rectangular type and preferably isof some standard size and which also functions aa part of the tubeenvelope. Section Il carries at its opposite ends flanges il and l! bywhich it may be readily connected into a standard waveguide transmissionsystem. The flange Il and if may include R. F. (radio frequency) chokesor any other desirable known features for assisting coupling. In thediode ahowninFig.1aportion iloftheinnerwnll of the top of waveguidesection It acts as the anode. Since ordinarily the metallic tubescoilprising a waveguide system are grounded. the energizing potentialfor this diode will preferably be applied as a negative potential to itscathode (filament Il). .Howeven if desired, the entire section Il may beD. C. insulated from the rest of the waveguide system so that it will bepossible to apply the energizing potential to it as a positivepotential. In either case the ma tion I! of the inner wall of thesection will lis at a higher potential than the diode-cathode.-`

l'br efficient operation it is essential that the inter-electrode spacefor this diode be vos! short. If the transit time from the cathode totheanodcisgraduallyincreaseditwillbenoted that when it is equal to aboutone-half of period corresponding to the center frequency of theoperating band, or, to be more exact. when it is equal to 3-5 radians atthat frequency. the noise current will be down very markedly. moreparticularly the mean squared noise current i?) willbedownbyo.andwillbedecreasingata rapid rate. The mean noise current may beconsidered as an integration of random curreit impulses each of which lsproduced during the transit of an individual electron from the cathodeto the anode. According to Fourier. if the transit times are very shortthe current im pulses will include many high frequency com,

ponente having significant magnitudes whereas Liftheyarelongthiswillnotbetrue. This, when the noise current dropsbecause of in creasesintransittimethelossismostlyinim high frequencycomponents. Accordingly it is desirable for the diode to have a shorttransit time. Moreover. it is desirable for the transit time to be shortfor mother reason, this being that its duration aifects the A. C. plateresistance ofthediodeinsuchamannerthatevenifit is operated withtemperature-limited emission ,it can seriously load the guide if thetransit timefb too long. But this of itself does not mean that theinterelectrode space must be short. since it is possible to decrease thetransmit time by i ncreasing the electron velocity. i. e.. by usinglarger and larger potential gradients between the cathode and the anode.However. if the dis-` charge space is over the full distance from thebottom to the top of a standard waveguide, the potential necessary for atransit time of less than 3.5 radians is so great ss to be impracticaland uneconomical.

Accordingly the present arrangement provid. for a very smallinterelectrode discharge space. Moreover. it provides the smalldischarge space without entailing any protrusion of the cathode into thedielectric transmission medium in the LFisures beingasection 1g section.v'Iothisenrithe cathode,whichinthe T... tu mm muwmmmmmmmmm a mmmmm.mm.m..mmmmmmm mmmmmmmmwmmmm @www u o :u r u n w m mamut m m y .mm mm..Mtn f.. mm www www@ mmwmmmmmmwmmwmmm mmmmdmmm mmmwmmmmmmmm wwwMmmmmwmmmwmmmmmmwmmmmmmmmMmmmmmmmmwmmmmmm mmmm wwmwmbwwwmwmmmwwmmwmm-mww.mmmmmmmmmmwmmmmmmww am? mim wmmmmm E@ mtmm.@wmmmmmwww.. u mn .m t en hE w m mummfmn.. mdwm.. mmd u mw .m @mm mmmmmmmwmmmmmmwmmmmmmmmmmmMmmmMmmm@wwwMmmmmmmmmmm my mmm m mmmmmwwm mmmmman m u w Mwm" magma mm mmm ..mmm m m m mmm mmm w. mm n?. am m m .am m mmm L?? w w m m m mmmmmmmmmmm mmmmmmmmmmmmmwm mm www L m mas m. my mmmmwmm-, Mmmm mmummmmwnm mmm mmmmmmmmwnmmx .um n wmmmm mmmmnwwLmemmmmmmmdmmm muffa. Mmmm .www mnmmmwmtmm ...Mmmmmmmmmwmwmmnmmmmmwmmm mmmwymm www .Mmmm .hmmm wwwmmmwwmarmmmxm n. m. am www@ s mrwwmmm mm mm .mmmmmmmmmvmmf n.mmmmm Mmmm.; m mm u m n amm .u u m @www mm.m. fmm www mm mm mm mmwww@mmmmmmwmmmmwwmmmmmwww mmmmmmmmmmw www ...u ,w.a um... m m my 1 ...an m ....aww n m Mmmm n.. d um my@ f m Ln .aummmlmmmmmnmnwmmmmm n MNM output ends according to principles known tothe waveguide art. If it should be desired to utilise the diode in thesame frequency range as that over which the embodiment of Fig. 1 is use-IuLalIthatisnecessaryistoaddtotheends of the section Ila two sections ofwaveguide which contain the long. tapered end portions so that. when thethree sections are connected together. the result will be the electricalequivalent of the diode of Fig. l. Obviously it is desirable that thebreak between auch attachable taperedendportionsandthebluntendstlbeassmallas possible.Forthisreasonthinvacuumsealasuch as mica windows, are to be preferredfor embodiments of this type. On the other hand. if itshouldbedesiredtooperatethediodeoveran extended band of frequencies orover a band of frequencies not entirely within the operating band of anembodiment of the Fig. i type. diiferent types of attaohable sectionsshould be connectedtotheendsofthediodesuchasimpedance transformerscontaining appropriately tapered for the ridge 88, or other transformlnadevices known to fthe art.

Although our improved diode has beendesorihedineonnectionwithitsuseasanoisediodeforthepm'poseofmakingcertaintestsandmeasurements. it is evident that adevice of this type may have various other applications wherever it isdesirable to maintain a certain circuit impedanceandhaveattbesametimeanelectron discharge device in this circuit without disturbing the.characteristics thereof. It willalsobeevidentthatinsteadofbeinglimitedto a two-element tube. other elements may be incorporated in our tube.Therefore, while we have indicated the preferred embodiments of ourinvention of which we are now aware and have also indicated enh certainspecinc applications for which our invention may be employed, it will beapparent that our invention is by no means limited to the exact formsillustrated or the use indicated, but that many variations may bemadeintheparticularstructureusedandthe purpose for which it is employedwithout departing from the scope of our invention as set forth in theappended claims.

What I claim is:

l. A ridge structure for a hollow conductor which enoloses an electrondischarge device wmprising a thin elongated ridge base. a ridge insertcarried by the central portion of the ridge base, with nelatlvely largeportions of its surface closely-juxtaposed to surfaces of said ridgebase. insulating material having a high dielectric constant interposedbetween said juxtaposedsurfaceswherebytheridgebaseandtheridgeinsertacecoupledastoltnenergybyalargecapacitancebutareisolatedastoD.C.,theridgeinsertoomprisingaprincipalportionandaminor insert carried by theprincipal portion but insulated therefrom as to D. C., an elongatedcathode having its respective ends directly connected electrically tothetwo portions of the ridge insert. and a recon in the ridge insertextending alongitforallofthelengthofsaidcathodeintermediate its endswhereby except for said ends saidcathodeisnotindirectelectricalcontactwith any conductive portion of the ridge structure.

2. A ridge structure for a hollow conductor which encloses an electrondischarge device com prisingathinelongatedridgebasehavingacentralportion of given height and tapering gradually in height from saidcentral portion toits two extremities, a ridge insert carried, bysaid'central portion with relatively large portions of its surfaceclosely-juxtaposed to surfaces thereof. insulating material having ahigh dielectric constant interposed between said juxtaposed surfaceswhereby the ridge base and the ridge insert are coupled as to R. F.energy by a large capacitance but are isolated as to D. C., the ridgeinsert comprising a principal portion and a minor insert carried by theprincipal portion but insulated therefrom as to D. C., an elongatedniament having its respective ends directly connected electrically tothe two portions of the ridge insert. and a recess in the ridge insertextending along it for all of the length of the filament intermediateits said ends whereby except for said ends said lament is not in directelectrical contact with any conductive portion of the ridge structure.

3. A ridge structure for a hollow conductor which encloses an electrondischarge device comprising a thin elongated ridge base, a ridge insertcarried by the central portion of the ridge base with relatively largeportions of its surface closely-juxtaposed to surfaces thereof,insulating material having a high dielectric constant interposed betweensaid juxtaposed surfaces whereby the ridge base and the ridge insert arecoupled as to R. l". energy by a large capacitance but are isolated asto D. C.. the ridge insert comprising a principal portion and a minorinsert carried by the principal portion. a filament having itsrespective ends directly connected electrically to the two portions ofthe ridge insert. the ridge insert being formed withashallow depressionalong its top surface between the points of connec tion of therespective ends of the mament wherebyexceptforitssaidendstheillamentisnotindirect electrical contact with anyof the conductive portion of the ridge structure, and means forsupporting the nlament under tension between the ends of the depressionto bridge it so that as toR.F.currentsthefilamentwillactasthe topsurface of the ridge'structure.

4. A ridge structure for a hollow conductor which encloses an electrondischarge device comprising a thin elongated ridge base, a ridge insertcarried by the central portion of the ridge base with relatively largeportions of its surface closely-juxtaposed to surfaces thereof.insulating material having a high dielectric constant interposed betweensaid juxtaposed surfaces whereby the ridge base and the ridge insert arecoupled as to R.. F. energy by a large capacitance but are isolated asto D. C., the ridge insert comprisingaprincipalportionandaminorinsertcarriedby the principal portion butinsulated therefrom as to D. C., a filament having its respective endsdirectly connected electrically to the two portions of the ridge insert.the ridge insert being formed with a shallow depression along its topsurface between the points of connection of the respective ends of thelament whereby except for its said ends the filament is not in directelectrical contact with any of the conductive portion of the ridgestructure. means for supporting the filament under tension between theends of the depression to bridge it so that as to R.. F. currents thefilament will act as the top surface of the ridge structure, the ridgeinsert being formed to denne a cavity for receiving an element of saidsupporting means consisting of a slightly loaded spring connected to oneend of the filament to keep it under tension, and a corrugated metalribbon connected between said one end of the asszooalargeportionsofitsnnfaoaeloselyduxtaposedto surfaces thereof. imulatingmaterial having a agr' eonduetortoapointatwhichitisjoinedtnanendofsaidridge.thetaperingoftheridsebeingsymmetricalinthatoneachofiendsitstopprlaoh one another from said centralportion so as smoothly to join one of said inner conductors. i3. Anelectron discharge device comprising an conductor, a ridge connectedinner wall of the hollow conan emissive surface. to support the cathodeits smilve surface adjacent to a portion of the opposite inner wall ofthe conductor which ananodeforthe deviceandwith saideconductoratleastoneoftheseals abutmgagainst ablunt end of the ridge.

l4.--An evacuatedelectrondischargedeviccincludingatubularanbdeofpredeterminedcross sus o mountedwiththeemlssivesurface thereofinsubstantially the same plane as adjacent surfaces of the support. j

I6. An electron discharge device including a tubular conductor.electromagnetic-enersy-permeable means hermeticaliy sealing the ends ofsaidV conductor, a cathode within said tubular conductor, said tubularconductor serving as an anode for said cathode. an elongated supportsupporting said cathode closely adjacent the inside ld surface `of'suidtubular conductor, said support having an enlarged central portionsupporting said cathode and tapered end portions, said tapered endportions serving as impedancetransfonnerswhensaiddevlceisutilinedinanl".

n system.

id. Anelectrondischargedevicecomprisingan envelope including a sectionof wave guide sealed at both of its ends withelectromagnetic-energypermeable material. emotion-receiving meansincluding an elongated surface extmding along the inside of a wall ofthe section of wave guide and facing toward the inside of its oppositewall to serve as an anode for the discharge device, said sectioncontaining an elongated ridge having a bottom side which is physicallyattached to said inside of said opposite wall in such a position that acentral portion of the top side of the ridgeregisterswithsaidelongatedsurfacetoactasa support for a cathode tocooperate with that surface, theheight of the ridge as measured betweenits top and bottom in its central portion being large enough so that insaid central portion its top is closely juxtaposed to said elongatedsurface while its height in iin end portions progressively lessens untilit is negligibly small at its two extremities, means providing directcurrent insulation and radio frequency capacitive coupling between saidinside of said opposite wall and at least the central portion of the topside of the ridge. a thermionically emissive surface carried on saidcentral portion of the top of said ridge in close juxtaposition to andfacing toward saidelongatedsurfacetoactasacathodeincooperationtherewith, means for heating said emissive surface by the use of anexternally supplied electrical current, said means including a resistivefilament and a heater lead connected to oneoftheendsthereofandextendingto aterminal on the outside of said envelope, said lead withinthe ridge between its top and bottom to be shielded therewithin andextending through said opposite side of the section of wave luide tosaid terminal.

17. An electron discharge device comprising an elongated hollowconductor, an elongated conducting ridge extending longitudinally withinsaid conductor. one transverse dimension of said ridgebeingalnsostasgreatasthecorrespondingdimension of said conductor. atleast one side edge ofsaidridgebeinglocatedinclosespaced relation withsaid conductor, the transverse dimensionofsaidrldseatrlghtanslestosaidnrstnamed being only a small fraction of the vlc. l ls s Ktominimil'ethereductionoftheimpedanceof said conductor due to thepresence of said ridge. andea cathode supported on said side edge ofsaid HARWICK JOHNSON. KENNETH R. DE REMER..

BefereneesCitedintheiileofthispatent UNlTlliDB'I'ATESPAmTB Number NameDate 2.122.538 Potter July 5, 1938 2.144.322 Heumann Jan. 17. i9392.157.952 Dallenbaeh May 9, 1939 2,402,184 Samuel June 18. i9462.463.308 Finke Mar. 1. i949 2.500.644 Johnson May 9. 1950 2.509.374Bunnein May 30. 1960

